The spatiotemporal modulation of gene expression using targeted light to activate antisense molecules promises to have an important impact in transparent model organisms, where irradiation can be specifically targeted visually to known anatomic landmarks. Irradiating selected cells within organs permits specific genes to be turned off at any time during the development of the organism with cell-scale resolution, thereby permitting an in depth spatiotemporal understanding of the role of particular genes in the whole organism. This also allows the study of genes essential in early development that otherwise result in a lethal phenotype. We have developed a commercial reagent, software and instrumentation platform for conducting spatiotemporal gene-control experiments. Leveraging off these initial successes, we now aim to further develop and commercialize a new generation of photoactivatable antisense reagents (PhotoMorph3.0" and PhotoPS3.0"). The proposed photoactivatable antisense reagents are based on morpholino or phosphorthioate oligomers that are protected on their exocyclic hydrogen bond donors and acceptors with photolabile caging groups that disrupt Watson-Crick pairing with a target mRNA. Light irradiation cleaves the caging groups, freeing the bases to participate in hybridization with the target. We hypothesize that exocyclic base protection will offer important advantages over other photoactivatable formats, including a 'tight'off-state and facile on-demand access using automation. The goal of this Phase I SBIR is to make the photoactivatable antisense chemistry robust for commercial-scale synthesis and implementation. The goal of the Phase II SBIR will be to develop validated and turn-key "tool-kits" for various developmental pathways (e.g. gut400, CNS500), where the basic phenotype of each photoactivatable antisense reagent will be described and made available in a public database for researchers. PUBLIC HEALTH RELEVANCE: The modulation of gene expression at different times and locations using targeted light to activate molecules promises to have an important impact in transparent model organisms, where irradiation can be specifically targeted visually to known anatomic landmarks. Irradiating selected cells within organs permits specific genes to be turned off at any time during the development of the organism with cell-scale resolution, thereby permitting an in depth understanding of the role of particular genes in different locations in the whole organism and at different times during its development. We now aim to further develop and commercialize a new generation of photoactivatable chemicals for doing this (PhotoMorph3.0" and PhotoPS3.0") that we believe will offer important advantages over others.